The present invention generally relates to a method and system for controlling the quality of a product produced by an injection molding production process and in particular, to a parametric release method and system that performs an analysis of the production parameters and removes defective product from the process when the production parameters exceed a predetermined control limit.
It is commonly known to monitor various process and product parameters to evaluate the quality of the product produced by an injection molding operation. Quality control through inspection of final product, for example, typically occurs downstream from the injection molding operation. Inspection of final product, however, does not take into account the molding process and any variability associated with the overall process. As a result, post-process product inspection fails to provide a mechanism to determine the factors contributing to any defective product produced.
Statistical process control (SPC) has also been applied to the injection molding process to monitor, measure and analyze process variation in order to determine whether the injection molding process is operating within control limits. The production process is typically halted when SPC determines an out of control condition allowing for the cause of the out of control condition to be identified and rectified before production is resumed. This results in significant production downtimes that are detrimental to production economies. Moreover, SPC does not have the capability to identify correlations between all the process variables that are monitored during production. It is therefore possible for an SPC-monitored process to produce undetected defective product during an aberrant cycle.
A need therefore exists for a system and method for analyzing production process parameters that determines whether a product produced by an injection molding process is defective and subsequently removes the defective product from the process. A need further exists for a defective product identification and removal system and method that operates without halting the entire production process.